It is hard to tell the real performance under vmware.
Our test shows that there is no big difference between linux kernel 2.4 & 2.6.
But we do find the benchmark result is much worse when ab in apache 2.0.x is used. So always use an "ab" from apache 1.3.x.
And we found linxu 2.6's poll implementation is not as good as that in 2.4, especially when you run the test tool in the same box. So for 2.6 kernel, "epoll" should be used instead of "poll".